1. Field of the Invention
The present invention relates to wireless communication, and more particularly, to an apparatus and method of managing a radio bearer in a wireless communication system.
2. Related Art
The 3rd generation partnership project (3GPP) long term evolution (LTE) which is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) has been introduced as 3GPP release 8. The 3GPP LTE uses an orthogonal frequency division multiple access (OFDMA) in a downlink and uses a single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE adopts multiple input multiple output (MIMO) having maximum four antennas. Research is now underway on 3GPP LTE-Advanced (LTE-A), which is a major enhancement to 3GPP LTE.
As a representative technology newly added in the LTE-A system, there are carrier aggregation and a relay. The carrier aggregation is used to flexibly expand an available bandwidth. The relay increases coverage of a cell, supports group mobility, and allows a user-centered network arrangement.
A radio bearer means a logical path provided by a radio interface protocol for transmitting data between user equipment and a network through a wireless channel.
The radio bearer is used to be defined only for the wireless channel between the user equipment and a base station. However, as the relay is introduced, two wireless channels, that is, a first wireless channel between the user equipment and the relay, and a second wireless channel between the base station and the relay, exists and the radio bearer for the two wireless channels needs to be defined.